Fix -Wimplicit-fallthrough warnings in netd

Test: atest netd_integration_test
Change-Id: Ib5ab9661fb429fdccd6a4c4b5893831ff5fe104e
diff --git a/resolv/res_mkquery.cpp b/resolv/res_mkquery.cpp
index 82c42d5..f747fce 100644
--- a/resolv/res_mkquery.cpp
+++ b/resolv/res_mkquery.cpp
@@ -131,7 +131,8 @@
      * perform opcode specific processing
      */
     switch (op) {
-        case QUERY: /*FALLTHROUGH*/
+        case QUERY:
+            [[fallthrough]];
         case NS_NOTIFY_OP:
             if (ep - cp < QFIXEDSZ) return (-1);
             if ((n = dn_comp(dname, cp, ep - cp - QFIXEDSZ, dnptrs, lastdnptr)) < 0) return (-1);